Rotation mechanism for rock drills



ATTORNEY Sept. 10, 1935. J. c. CURTIS ROTATION MECHANISM FOR ROCK DRILLS Filed April 11, 1932 7 Z A J W M Z w M m MIN, m H 1% 6 mm 1 i m q H J 4 E 09 M N V H H m 2 $7. 0 %\A a, J!

Patented Sept. 10, 1935 UNETED STA'i'Efi QFFECE John C. Curtis, Cleveland, Ohio, assignor to The Cleveland Rock Drill Company, Cleveland, Ohio,

a corporation of Ohio Application April 11, 1932, Serial No. 604,376

Claims.

This invention relates broadly to rock drills of the fluid actuated type, but is more particularly concerned with the rotation mechanism therefor.

One of the objects of this invention is to provide a rock drill with a rotation mechanism whereby the piston is held against rotation, and its reciprocatory motion is transformed into a rotary motion transmitted to the cutting tool, reducing thereby the frictional resistance of the piston within its cylinder and increasing the efficiency of the machine.

Another object of this invention, is to procure a rock drill with an efficient rotation mechanism, whereby the rotary motion transmitted to the cutting tool may be readily controlled by the operator when the rotative movement of the cutting tool becomes restrained While drilling rock or similar material of variable density.

Further objects and advantageous features will be apparent from the following detailed description considered in connection with the accompanying drawing, wherein similar characters of reference designate corresponding parts and wherein:

Fig. 1 is a longitudinal sectional view of a rock drill embodying the invention, the different elements being shown in their normal operating position.

Fig. 2 is a cross sectional View taken on a plane indicated byline 2-2 in Fig. 1 and illustrating the relation assumed by the parts during the rearward movement of the piston.

Fig. 3 is a view similar to Fig. 2 illustrating the relation assumed by the parts during the forward movement of the piston.

Fig. 4 is a cross sectional view taken upon a plane indicated by line 44 in Fig. l and illustrating the different parts in operative position.

Fig. 5 is a view similar to Fig. 4 but illustrating the different parts in inoperative position.

The rock drill illustrated in the drawing comprises a cylinder 1 B having a piston l l reciprocable therein. The piston H is formed with a reduced portion or stem 52 being provided toward its end with a plurality of equally spaced helical splines l3. Maintained in pressed fit engagement within the front end of the cylinder l0, there is a stationary bushing M, within which the stem I2 is reciprocably guided. The forward end of the bushing M, is terminated by an enlarged cylindrical portion or flange 15, in abutting relation with the front cylinder face to limit the penetration of the bushing within the cylinder. Mounted in tight engagement upon the bushing flange l5, there is a front housing It provided with a bore ll, and an enlarged counterbore 58, forming at their intersection an annular shoulder IS. The bore H, and counterbore l3, are conveniently machined to properly receive a chuck 28, being rotatably mounted therein and having its longi- 5 tudinal displacement limited in one direction by its engagement with the annular shoulder 59. The chuck ll is provided with a bore 2! formed of a hexagonal cross sectional area, Within which is slidably mounted the corresponding end portion of a drill steel 22, which end is adapted to receive the blows of the piston l l The bushing is is provided with a counterbore 23, within which there is rotatably mounted a sleeve 24 extending within a counterbore, formed Within the rearward portion of the chuck 20. The depth of these counterbores is such as to provide for a restricted longitudinal displacement of the sleeve 24, the bottom of these counterbores affording thereby a thrust bearing surface limiting the longitudinal movement of the sleeve 24. Internally, the sleeve 24 is provided with a plurality of equally spaced helical splines 25 defining intermediate thereof a plurality of helical grooves 26, within which are slidably engaged the helical 25 splines 13, formed upon a portion of the pistons stem 2. The external wall of the sleeve 26 is provided with a pluralityof equally spaced longitudinally disposed recesses 21, having the bottom thereof forming a portion of a true circle. One 30 side wall 28 of these recesses is manufactured normal to the circumference of the sleeve While the other side Wall is deviated from the wall 28 to constitute an inclined plane or wall 29. Leading inwardly from each of the recesses 2?, there is a bore within which there is disposed a compression spring 38, and slidable plungert 5. Within the recesses 21, there is a roller 32, of a diameter somewhat smaller than the total depth of the recesses. The roller 32 is constantly forced outwardly by reason of its engagement with the spring pressed plunger 3|. The Wall of the chucks counterbore is provided with a plurality of longitudinally disposed arcuated recesses or grooves 33, within which are engageable the rollers 32. These rollers are somewhat shorter than the depth of the chuoks counterbore, and are maintained therein by a bearing plate 34 interposed between the bushing l5 and the chuck 2E3.

Secured within the rear end of the cylinder i ii, there is a valve block 35, within which is reciprocably mounted .an inlet fluid controlling valve 36. The valvular mechanism being no part of the present invention, no further description of $ame is thought necessary other than directing the attention to a plurality of passages 31, through which motive fluid is admitted to the valvular mechanism and to the cylinder E9, to effectuate the reciprocation of the piston II in a manner common to tools of this type.

Maintaining the valve block 35 in a desired position, there is a backhead 38 secured to the cylinder IE3 in any suitable manner and having rotatably therein a throttle valve 39 for control ling the admission of motive fluid to the valvular mechanism.

The enlarged portion or bell of the piston I I is provided with a screw threaded bore 40 within which there is secured in screw tight engagement a splined nut 3!, the splines thereof being slidably engageable with the grooves of a splined stem 52, secured within the backhead 38 and extending through the valve block 35 into the cylinder I0 a sufficient distance to remain in engagement within the nut 4! when the piston iI is at the extreme end of its forward travel. The stem 42 is provided with a head 43 associated with the backhead 32 and valve block 38 to prevent the longitudinal movement of the stem within the cylinder IE. Radially disposed within this head, there is a plurality of shallow recesses M.

Adjacent the stems head 43, the backh-ead E8 is provided with a radially disposed slot 45 within which there is slidably mounted a pawl 4-5 which is capable of engagement within the recesses M. This pawl is constantly forced toward the stems head 53 by its association with a compression spring 21. The pawl 4% is formed with an integral trunnion 48 capable of operative engagement with a cam 49, which is rotatably mounted within a bore 56, provided in the backhead 38. This cam is terminated by a knurled disk or handle 5! to permit its easy manual operation.

In the operation of the mechanism, assuming the different elements to be positioned as illustrated in Fig. 2 and Fig. l, motive fluid being admitted into the cylinder IE will produce the reciprocation of the piston I I in manner common to tools of this type. During its reciprocation, the piston II is kept from rotating by the sli-dable engagement of its splined nut II within the grooves of the splined stem G2, which is locked against rotation by the pawl 45, maintained within one of the recesses 34, by the action of the compression spring ll. When the piston I I is moved leftwardly or during its rearward stroke, rotary motion is imparted to the sleeve 24 by reason of the slidable engagement of the pistons helical splines I3 within the corresponding helical grooves 26 of the sleeve 24, thus transforming the longitudinal motion of the piston I I into a rotary motion of the sleeve 24. The helical splines I3 of the piston II are machined in such a way as to produce, during the rearward stroke of the piston, a counterclockwise rotation of the sleeve 26 or a rotation in .a direction illustrated by the arrow in Fig. 2. The spring pressed plunger 3|, acting against the rollers 32, have the tendency to maintain these rollers away from the recesses 21 or within the grooves 33 of the chuck 25. Due to the rotary motion imparted to the sleeve 24, the walls 29, of the recess 21, will come into engagement with the rollers 32, within the grooves 33, thus forcibly maintaining said roller within said groove to prevent the relative rotation of the sleeve 26 with respect to the chuck 25, and affording thereby the consequential rotation of the chuck 28 and drill steel 22. a

When the piston is moved rightwardly or duragainst rotation by the pawl 46.

ing its forward stroke, the sleeve 24, by the engagement of the pistons splines I3 within the sleeve grooves 26, will be rotated in a clockwise direction or in the direction illustrated by the arrow in Fig. 3. The torque resistance of the chuck 28 being greater than the force necessary to compress the springs 30, the plunger 3!, by reason of the rotation of the sleeve 25 in a clockwise direction, will be pushed inwardly to compress the springs 33 and allow the engagement of the rollers 32 within the bottom of the recesses from the rotary motion of the sleeve 2G, will be acting against each other in a radial direction, preventing thereby the binding of the chuck it within its housing Hi.

When drilling in abrasive material, the rotative movement of the cutting tool may become restrained thus necessitating the application of some readily operable means to prevent such rotative movement. The rotative movement imparted to the drill steel 22 maybe controlled by manipulating the cam e9. As explained. previously the reciprocation of the piston I I is transformed into a rotary motion due to the engagement of the piston I I with the splined stem 42 which is locked To prevent the rotation of the drill steel 22, the cam d9 may be rotated and positioned as illustrated in Fig. 5. The cam acting upon the trunnion 48 will cause the withdrawal of the pawl 28 from one of the recesses 44 and allow the rotation of the splined stem 42. The torque resistance of the chuck 20 being greater than the torque resistance of the piston II, it will readily be understood that the rotative movement resulting from the reciprocation of the piston will now be transmitted to the piston and splined stem 42, preventing thereby the rotary motion of the chuck 2D and drill steel 22.

When it is desired to rotate the drill steel, the cam 49 may again be turned and positioned as illustrated in Fig. 4. The pawl 46 by the action of the compression spring 4'! will be shoved to ward the splined stems head 43, and into one of the recesses 44 to prevent the rotation of the splined stem 42 and piston I I, thus allowing the rotary motion of the drill steel 22.

Although the foregoing description is necessarily of a detailed character, in order to completely set forth the invention, it is to be understood that the specific terminology is not intended to be restrictive or confining and it is to be further understood that various rearrangements of parts and modification of structural detail may be resorted to without departing from the scope or spirit of the invention as herein claimed.

I claim:

1. In a drilling motor, a housing having a cutting tool slidably and rotatably mounted therein, a cylinder having a piston reciprocable therein and capable of rotation, a rotatable member normally held against rotation associated with said piston for preventing the rotative move- These two rollers are disposed? opposite to each other, thus the forces resulting ment of the latter, means for transforming the reciprocatory motion of said piston into a rotary motion and transmitting said last mentioned motion to said cutting tool, and means for releasing said member thus permitting the rotation of said piston and consequently preventing the rotary motion of said cutting tool.

2. In a drilling motor, a housing having a cutting tool rotatably mounted therein, a cylinder having a piston reciprocable therein and capable of oscillation, a rotatable member normally held against rotation associated with said piston to prevent its oscillatory movement, means for transforming the reciprocatory motion of said piston in an oscillatory motion, means for transforming said oscillatory motion in a rotary motion and transforming said last motion to said drilling tool, and means for releasing said member thus permitting the oscillatory movement of said piston and consequently preventing the transformation of said last mentioned movement in a rotary motion.

3. In a drilling motor, the combination with a chuck capable of rotation, of means for effecting said rotation including a piston reciprocable within said cylinder, helical splines upon a portion of said piston, a sleeve operatively associated with said splines and rotated thereby during the reciprocatory motion of said piston, a ratchet mechanism for transmitting the rotary motion of said sleeve to said chuck, a rotatable member normally held against rotation upon which said piston slides to prevent the rotation of the latter during the normal operation of said ratchet mechanism, locking means movable in or out of engagement with said member to prevent or permit the rotation of the latter, and further means for actuating said locking means.

4. In a drilling motor, the combination with a chuck capable of rotation, of means for effecting said rotation including a piston reciprocable within said cylinder, helical splines upon a portion of said piston, a sleeve operatively associated with said splines and rotated thereby during the reciprocatory motion of said piston, a ratchet mechanism for transmitting the rotary motion of said sleeve to said chuck, a rotatable member normally held against rotation associated with said piston, means for constantly preventing the relative rotation of said member and said piston, recesses in said member capable to receive a spring pressed plunger for holding said member and piston against rotation during the normal rotation of said chuck, and manually operated means for withdrawing said detent from said recesses permitting thereby the rotation of said member and said piston and preventing the rotation of said chuck.

5. In a drilling motor, the combination with a chuck capable of rotation, of means for effecting said rotation including a piston reciprocable within said cylinder, helical splines upon a portion of said piston, a sleeve operatively associated with said splines and rotated thereby during the reciprocatory motion of said piston, a ratchet mechanism for transmitting the rotary motion of said sleeve to said chuck, a splined stem normally held stationary upon which said piston slides to prevent the rotation of the latter during the normal rotation of said sleeve, and means permitting the rotation of said stem and consequently of said piston thus preventing said helical splines from imparting rotation of said sleeve.

JOHN C. CURTIS. 

